Rehabilitation and restoration of old steel railway bridges: Laboratory experiment and field test

Preventive maintenance on aged steel railway structures is all important due to their long service time after completion. This paper introduced a strengthening method for old steel railway bridges by using rubber-latex mortar, glass fiber reinforced polymer (GFRP) plates, lightweight rapid hardening concrete, and reinforcing bars. Both laboratory tests and field tests were performed to confirm the effects of the present strengthening method. In total, two old railway bridges were employed in this study. One of them has been in service for around 100 years. The static loading test was performed in the laboratory. Experimental results, including load-deflection response, strain distribution on the structural steel, GFRP plates as well as concrete, were given and compared between the original steel railway bridge and the strengthened bridge. Theoretical results were also provided to make a comparison with the experimental results. Both the experimental and theoretical results indicated that the present renovation method could greatly enhance the rigidity and reduce the stress levels of old steel members, resulting in the extension of the residual service life of the old steel railway bridge. In addition, field tests were performed on the other old railway bridge, which has been used for 86 years, and stress variation on the railway bridge under the running train was measured and the effects of the present strengthening method in the real service condition were also confirmed.